Electron beam evaporator



Sept 16, 1969 H|FUM| v'MMURA ETAL 3,467,057

ELECTRON BEAM EVAPORATOR Filed July 25, 1967 2 sheets-sheet INVENTORS QW/fwf/QY ATTORNEY United States Patent O 3,467,057 ELECTRON BEAM EVAPORATOR Hifum Tamura, Hachioji-shi, and Hirokazu Kimura, K-

ganei-shi, Japan, assignors to Hitachi, Ltd., Toky0, Japan, a Japanese corporation Filed July 25, 1967, Ser. No. 655,939 Claims priority, application Japan, July 27, 1966, 41/ 48,799 Int. Cl. C23c 13/12; H01j 37/20 U.S. Cl. 11S-49.1 12 'Claims ABSTRACT 0F THE DISCLOSURE An electron beam evaporator having means for establishing a static deflecting field between an electron gun and a piece of vaporizing material by a voltage proportional to the electron beam accelerating voltage so that the static field deiiects downwardly the path of the laterally emitted electron beam, and material particles vaporized by the electron bombardment can be deposited on a substrate disposed above the piece of vaporizing material. Back-scattered electrons dispersed from the piece of vaporizing material can be effectively eliminated by a scattered-electron blocking field established in the space between the substrate and the piece of vaporizing material.

BACKGROUND OF THE INVENTION Field of the invention-This invention relates to particle evaporators employing electron beams, and more particularly to a novel and improved electron beam evaporator which is so constructed as to give a large effective evaporated surface area, to have a large evaporation capacity, and to effectively eliminate back-scattered electrons dispersing from a piece of vaporizing material, thereby preventing these back-scattered electrons from reaching a substrate on which such vaporizing material is to be evaporated.

Description of the prior art-Apparatus for directing an electron beam toward a piece of vaporable material to heat and vaporize the same, thereby depositing vaporized particles of the vaporable material on a substrate have been proposed in a variety of types and have been formerly known in the art. However, all of these formerly known apparatus have been defective in that backscattered electrons including refiected electrons and secondary electrons are dispersed from the piece of vaporable material bombarded by the electron beam and those back-scattered electrons reaching the substrate affect adversely the property of the evaporated film. Further, prior art apparatus of a certain kind have been defective in that a wide effective evaporated surface area cannot be obtained.

SUMMARY OF THE INVENTION It is therefore the primary object of the present invention to provide an electron beam evaporator of novel and improved structure which is entirely free from the above defects encountered with the prior art apparatus.

Another object of the present invention is to provide an electron beam evaporator of novel and improved structure which can give a wide effective evaporated surface area and can effectively prevent back-scattered electrons from reaching a substrate.

A further object of the present invention is to provide an electron beam evaporator in which means are provided to suitably vary the intensity of the electron beam and to permit simultaneous or alternate deposition of different vaporizing materials.

ICG

In order that the above and other objects, features and advantages of the present invention as well as improvements effected by the invention over the prior art apparatus can be clearly understood, various embodiments of the present invention as compared with the prior art apparatus will be described with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 and 2 are schematic views showing the structure of prior art electron beam evaporators.

FIGS. 3a, 3b and 3c are schematic sectional views showing various embodiments in one form of the electron beam evaporator according to the present invention.

FIG. 4 is a plane view showing one form of magnetic field generating means for the removal of back-scattered electrons adapted for use in the apparatus of the present invention.

FIG. 5 is a schematic sectional view showing another embodiment according to the present invention.

FIG. 6 is a schematic view showing part of a further embodiment according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order that the present invention can be clearly understood, a brief description of the prior art apparatus will first be given hereunder. A prior art electron beam evaporator shown in FIG. l employs the so-called Pierce-type electron gun which comprises a cathode filament 11, a cathode electrode 12 and an anode electrode 13. In this electron beam evaporator, a high voltage of negative polarity is applied to the cathode, and a piece of vaporizing material 15 is supported on a grounded support 10. The piece of vaporizing material 15 is disposed at a position at which the vaporizing material piece 15 and the cathode filament 11 are unobstructedly opposite to each other in order to establish a direct straight path therebetween, and a substrate 16 on which the vaporizing material is to be deposited is disposed at a position above the piece of vaporizing material 15 in a suitably spaced relation from the path of the electron beam 14.

The electron beam 14 emitted from the electron gun impinges against the piece of vaporizing material 15 so that it heats and vaporizes the vaporizing material piece 15. Vaporized particles 17 scatter in every direction, but in this case the scattered particles 17 show the highest distribution in the direction of the path of the electron beam 14. However, in view of the fact that the substrate 16 cannot be disposed in the region of the highest scattered particle distribution, it is inevitable that the effective evaporated surface area is quite limited and uniformity of film thickness is hard to obtain. Furthermore, arrival of back-scattered electrons 18 at the surface of substrate 16 together with the vanorized particles 17 scattering from the vaporizing material piece 15 produces an undesirable phenomenon namely that cracks develop in the evaporated film deposited on the substrate.

An electron beam evaporator commonly called the selfaccelerated electron gun type as shown in FIG. 2 has also heretofore been known in the art. This type of electron beam evaporator has such a structure that electrons 24 emitted from a circular cathode filament 21 impinge against an anode electrode 25 while they are accelerated and deflected by the action of an accelerating electric field established by a cathode electrode 22 and the anode electrode 25. In this apparatus, the anode electrode 25 is formed from a vaporizing material and is therefore heated so as to vaporize when bombarded by the electron beam 24 so that vaporized particles 27 are scattered through a limited passage-defined by an aperture 29 in the cathode electrode 22toward the substrate 26 disposed opposite to the anode electrode 25. In the apparatus of FIG. 2 also, an adverse effect due to backscattered electrons 28 is observed as was the case for the apparatus shown in FIG. 1. Thus, in the apparatus of FIG. 2, the effective evaporated surface area is limited by the diameter of the 'aperture 29 provided in the cathode electrode 22. Enlargement of the aperture diameter in an effort to expand the effective evaporated surface area has a defect in that particles vaporized from the filament 21 reach the substrate 26 and deposit an impurity on the evaporated film on substrate 26. Furthermore, high -energy electron current is generally required in order to increase the deposition rate and to improve the evaporation capacity. In view, however, of the fact that such a type of apparatus has a limited perveance, the accelerating voltage must necessarily be raised to attain the above purpose, and there arise many difficulties including the problem of electrical insulation against such a high voltage and the problem of discharge between the closely spaced cathode electrode and anode electrode. Another undesirable fact encountered With the use of the above apparatus is that the deposition rate varies depending on the shape of the piece of vaporizing material.

In order to eliminate the defects encountered with such prior art apparatus and to attain the objects of the present invention, the el-ectron beam evaporator according to the present invention is so arranged that a substrate on which a vaporizing material is to be deposited is disposed at a position where the substrate is not straightly opposed. by an electron beam source but is directly opposed by a piece of vaporizing material and the electron beam emitted from the electron beam source is suitably deflected so as to bombard the piece of vaporizing material.

In addition to the above arrangement, means may preferably be provided in a region defined between the piece of vaporizing material and the substrate to deflect back-scattered electrons so that these undesirable electrons cannot utterly reach the substrate.

Referring now to FIGS. 3a, 3b and 3c, various preferred structures of the improved electron beam evaporator according to the present invention will be described.

In FIG. 3a showing an embodiment according to this invention, the electron beam evaporator includes an electron gun consisting of a cathode filament 31, a cathode electrode 32 and an anode electrode 33 which are laterally arranged in an evacuated vessel (not shown). A pair of defiecting electrodes 35a and 35b forming a static defiector are disposed opposite to each other at positions below and above the line of emission of an electron beam 34 lemitted in a lateral direction from the electron gun. The lower defiecting electrode 35a is formed integrally with the anode electrode 33, while the upper deflecting elec trode 35b is formed integrally with the cathode electrode 32 by an electrical conductive plate 41. Accordingly, the electron beam 34 passing through the static defiector is defiected downwardly beyond the beam emission line by the action of a static deflecting field established by an electron beam 'accelerating voltage applied across the cathode and anode electrodes, and since this static de fiecting field varies with a variation in the beam accelerating voltage, the electron beam 34 follows a fixed beam trajectory in spite of any variation in the beam accelerating voltage.

A piece of vaporizing material 36 placed on a Crucible 42 is so disposed as -to lie in the fixed electron beam trajectory described above, and the Crucible 42 carrying the vaporizing material piece 36 is supported on a base 43 so that the piece of vaporizing material 36 is equipotential with respect to the anode electrode 33. The piece of vaporizing material 36 is vaporized through the borni bardment of the electron beam 34 coming obliquely from above as shown, and the vaporized particles 37 are scattered chiefly in an upward direction. A substrate 38 on which the vaporizing material is to be deposited .is held in position by a suitable holding member 49 and is disposed at a position above the piece of vaporizing material 36 and above the electron beam emission line. Furthermore, according to the present embodiment, the upper defiecting electrode 35i) is extended over the piece of vaporizing material 36 in order that a direct straight path of electrons may not `be formed between the electron gun and the substrate 38. The substrate 38 is disposed above the extension of the upper defiecting electrode 35b, and an aperture 46 is bored through the extension to form a direct straight path of vaporized particles between the piece of vaporizing material 36 and the substrate 38.

Further, a support member 42 for the vaporizing material piece 36 and an electric conductive support member 48 which supports the lower defiecting electrode 35a, are mounted on the electric conductive base 43 and thereby kept at the same potential. A terminal 44 of the cathode 32 also works as a support member which supports the cathode filament 31 through an insulator 45.

Although it is desirable that the cathode electrode 32 and the upper deflecting electrode 35b, and the anode electrode 33 and the lower defiecting electrode 35a are mechanically connected to each other, respectively, there is no need of integral connection therebetween if they are electrically connected to each other to be respectively equipotential. Further, means such `as screw means may be additionally provided to permit suitable adjustment of the spacing between the cathode electrode 32 and the anode electrode 33 and the position of the deflector rela tive to the electron gun so that the electron beam trajectory may thereby be freely varied.

By way of example, the embodiment shown in FIG. 3a will be described on a more materialized lbasis by using actual numerical values. A tantalum foil 20p thick and 2.5 mm. wide is employed to form the cathode filament 31, and a D.C. current of l5 to 20 amperes is supplied from a D.C. power supply E1 to heat the cathode filament 31. Alternatively, an A.C. power supply may be employed for the purpose of heating. One end of the cathode elec trode 32 and one end of the cathode filament 31 are connected with each other by grounded electrical conductor 44. A high D.C. voltage which is by 2() kv. more positive than the cathode electrode 32 is applied to the anode electrode 33 from a power supply E2.

Suppose now that the cathode electrode 32 and the anode electrode 33 are spaced apart about 20 mm. Then, the perveance is in the order of l0J1 to 10-a a./v.3/2, and an electron beam of about 50 milliamperes can be obtained. Thus, the electron beam having -a diameter of 2 to 5 mm. bombards the piece of vaporizing material 36 which is spaced about mm. from the cathode electrode 32 and is disposed at a position about l2 mm. beneath the electron beam emission line. In an experiment made by the inventors, a plurality of rectangular substrates of glass were disposed in a plane which was spaced about 350 mm. above the piece of vaporizing material 36 and had a diameter of about 400 mm., `and a refractory material such as silicon or tantalum was used as the vaporizing material. In this experiment, a remarkably uniform evaporated film could be obtained on each of the glass subm strates. In the present embodiment, the electron beam accelerating voltage may be a D.C. or A.C. half-Wave rectified voltage of the order of 5 to 30 kv.

It will be appreciated that the above structure is ad-l vantageous in that the static detlector can develop a static deflecting field without any necessity to provide an exclusive power supply, the energy of the electron beam can be freely varied while maintaining the piece of vaporizing material 36 at a fixed position, and the extension of the upper defiecting electrode 35b acts as a shield lagainst back-scattered electrons emitting from the piece of vapor izing material 36, thereby effectively preventing the backscattered electrons from reaching the substrate 38.

More precisely, the greater part of back-scattered elec= trons dispersed from the piece of vaporizing material 36 by being bombarded by the electron beam 34 is distributed in the incoming direction of the electron beam 34 `and in a direction symmetrical to the above direction. Since, 1n the present embodiment, the structure is such that the piece of vaporizing material 36 is bombarded by the electron beam 34 coming obliquely from above, most of the back-scattered electrons are dispersed in the direction of the incidence angle of the electron beam 34 and in a direction symmetric-a1 to the incidence angle as shown by 39, and few electrons are dispersed upwardly from the piece of vaporizing material 36. Such few electrons are arrested by an electric field established by the upper deflecting electrode 35b at earth potential and the piece of vaporizing material 36 at high positive potential and are thus obstructed to reach the substrate 38.

Vaporizing material deposition similar to the case of the first embodiment shown in FIG. 3a can be effected when the anode electrode 33 and the piece of vaporizing material 36 are held -at earth potential, while a high negative voltage of the order of 5 to 30 kv. is applied to the cathode electrode 32. In such a case, a sufficiently satisfactory evaporated lilm could be obtained with silicon, but an evaporated film obtained with tantalum was somewhat inferior in property to that obtained in accordance with the first embodiment. Itwas found that such a detrimental effect resulted from the undesirable arrival of backscattered electrons at the substrate.

A second embodiment shown in FIG. 3b can more effectively eliminate such back-scattered electrons. Actually, this embodiment comprises a combination of the first embodiment and a deflecting means for more effectively eliminating back-scattered electrons. Similar reference numerals are used in FIG. 3b to denote similar parts appearing in FIG. 3a.

In FIG. 3b a magnetic field generating means 40 is provided on an upper defiecting electrode 35b in order to impart to back-scattered electrons a magnetic field H in a direction at a right angle with respect to the moving direction of the back-scattered electrons, for example, in a direction marked (D directed from behind the paper-to the viewer in FIG. 3b. Since this magnetic field H'imparts to the back-scattered electrons a deflecting action in a direction at a right angle with respect to the moving direction of these electrons, arrival of these back-scattered electrons at the substrate to be evaporation deposited with a vaporizing material can be avoided. The magnetic field generating means referred to above may be a rectangular frame 51 of pure iron as shown in FIG. 4, in which parts of opposite sides 52 and 53 are made to permanent magnets 54 `and 55 so that the N-poles and S-poles of these magnets are coupled through pure iron to establish a parallel magnetic field running in the direction of an arrow 56. The thus structured magnetic field generating means is mounted on the defiecting electrode 3511 in a manner to surround an aperture 46 through which vaporized particles from a piece of vaporizing material 36 can pass toward a substrate 38.

According to the second embodiment of the invention, the deecting electrode 35b is situated at a position suitable for the deflection o'f back-scattered electrons and has sufficient mechanical strength to support the magnetic field generating means 40. It is therefore possible to impart an especially effective deflectin-g action to the backscattered electrons passing through the region defined by the deflecting electrode 35b. It will be obvious for those skilled in the art that the electron deflecting means for the elimination of back-scattered electrons is in no way limited to the above structure and various electric field generating means as well as various types of magnetic field generating means utilizing permanent magnets, electromagnets and the like may be employed for the purpose.

Employment of the magnetic field generator or electric field generator which functions solely for the elimination of back-scattered electrons may be disadvantageous in' that the electron beam Ievaporator according to the present invention may become complex in its structure and expensive. It is therefore desirable that the static deflecting electrode for the electron beam deflection is constructed so as to have an additional function of deflecting the backn scattered electrons.

An embodiment having such a structure is shown in FIG. 3c in Which similar reference numerals are used to denote similar parts appearing in FIG. 3a.

In the present embodiment, an upper static deflecting electrode 35h has a portion 35h thereof rising upwardly at a right angle with respect to the remaining portion of the deflecting electrode 3r5b, and another dellecting elec trode 50, which is grounded, is disposed in substantially parallel relation with the upstanding portion 35b so as to define therebetween a direct straight path of vaporized particles 37 from a piece of vaporizing Imaterial 36 toward a substrate 38. Since an electric field, lying in a direction substantially intersecting the direction of the path from the piece of vaporizing material 36 toward the substrate 38, is established between the electrodes 35b and 50, the back-scattered electrons 39 are deflected in a manner as shown and they cannot reach the substrate 38.

As will be apparent from the above description, the present Iembodiment attains excellent effects in that means for eliminating back-scattered electrons can be accomplished by an extremely simple structure and there is no need to provide an exclusive energizing power supply for the back-scattered electron eliminating means. Furthermore, the above electrode 50 may be substituted by, for example, a belljar wall which is at the ground potential in a belljar (not shown).

It will thus be understood that the electron beam evaporator according to the present invention can satisfactorily provide a defiected electron beam in spite of such a simple structure and the energy of the electron beam can be varied depending on the conditions including the property of vaporizing material and the desired thickness of an evaporated film. Furthermore, due to the fact that the voltage for establishing the deilecting electric field is relatively high, a sufficient degree of deflection can be obtained even with a relatively small deflecting electrode. The above feature has the advantage; that the passage aperture 46 for vaporized material particles can be enlarged and the effective evaporated surface area can thereby be widened. Moreover, since there is no direct straight path between the electron beam source and the substrate in the apparatus according to the invention, there is utterly no fear that matters vapo-rized from the cathode filament may attach to the substrate.

According to the invention, a plurality of the basic structures as described above may be suitably combined to provide a composite electron beam evaporator.

FIG. 5 schematically shows the structure of an embodiment comprising a combination `of a plurality of electron beam systems. In FIG..5 the embodiment is shown as having a structure in which two electron beams 34 and 34 bombard the same piece of -vaporizing material 36. In FIG. 5 similar reference numerals are used to denote similar parts appearing in FIG. 3a. By use of a plurality of electron beams in this manner, it is possible to increase the energy usable for the fusion of vaporizing material and it is also possible to realize the use of a refractory material and the deposition of a thickly evaporated film which has heretofore been impossible wit-h the prior evaporator employing a single electron beam. In fusing a piece of vaporizing material place-d on a vaporizing material carrier, a plurality of electron beam systems may be disposed on a circle drawn about the vaporizing material piece so that the electron beams can be concentrated onto the vaporizing material piece and the beam systems may be simultaneously or successively placed in operation to easily effect the desired deposition of the vaporizing material.

In many cases, an evaporated film of a single kind is commonly formed on a substrate, but in some cases it is necessary to form a plurality of films of successively varying elements on yone and the same substrate. In other cases, it may be necessary to simultaneously form an evaporated film consisting of a plurality of component elements onl one and the same substrate. The present invention exhibits a remarkably prominent effect in case a plurality of vaporizing materials are simultaneously or successively evaporated on one and the same substrate. When, for example, it is desire-d to deposit two kinds of vaporizing materials on a substrate, the electron beam evaporator according to the invention may be so arranged that separate electron beams 34 and 34 are directed toward the respective vaporizing materials 36 and 36 in order to successively or simultaneously fuse the vaporizing materials as shown in FIG. 6. By virtue of the above arrangement, the respective materials can be vaporized at a desired rate under optimum conditions because the electron beams especially suitable for the respective materials can be supplied. Since, in this case, a deflected beam is especially used as the electron beam in accordance with the invention, the pieces of vaporizing materials can be disposed with a comparatively large degree of freedom and the effective evaporated surface area can be widened. The fact that a substrate 38 on which the vaporizing materials are to be deposited can be disposed directly opposite to the pieces of the vaporizing materials is especially advantageous in that the substrate 38 can receive the vaporized material particles dispersed from the plurality of vaporizing sources.

There may be various modes of arrangement when a plurality of electron beam systems are disposed. The electron =beam systems may preferably be disposed in a manner to surround a piece of Vaporizing material in case the number of the electron beam systems is considerably large. However, when the number of the electron beam systems is small, it is preferably, in view of the desired compactness and small size of the apparatus, that these electron beam systems are arranged to direct the electron beams in substantially the same direction. However, it is apparent that, in any of the above cases, the various notable effects of the inventive structure can be exhibited effectively.

In case of the structure employing a plurality of electron beams as shown by the embodiment in FIG. 5, it is effective to employ a magnetic field generating means 40 as illustrated as the second deflecting means for eliminating the back-scattered electrons.

Although the embodiments refered to hereinbefore have been illustrated as having a structure in which an electron gun or guns are horizontally disposed and a substrate and a piece or pieces of vaporizing materials are vertically disposed opposite to each other, it will be understood that the illustration is merely made fo-r the convenience of showing relative positional relations between these elements. It will be further :understood that the vaporizing material and the substrate on which the vaporizing material is to be deposited to cooperate with the apparatus of the invention, and various changes and modifications may be made in the means for holding these elements without departing from the spirit and scope of the present invention.

What is claimed is;

1. Apparatus for depositing vaporable material on a substrate by using at least one electron beam, which comprises:

(a) an evacuated vessel;

(b) at least one source emitting an electron beam along a straight path in the vessel;

(c) at least one beam deflection means for deflecting the electron beam emitted by the source in a direction which .is substantially at right angles to the straight path of the electron beam so that the electron ibeam is gradually deflected to deviate from the straight path thereof as it advances under the influence of the deflection means;

(d) means for holding at least one piece of vaporable material to be deposited in the vessel in the path of the deflected electron beam so that the vaporable material is struck by the electron ibeam and vaporized at that portion whereon the electron beam strikes; and

(e) means for supporting in the vessel at least one substrate positioned opposite to the straight path of the electron beam from the piece of vaporable material in a direction substantially opposite to that of said deflected beam, whereby only the vaporized particles of the material are permitted to reach the substrate,

(f) said electron beam source comprising means for emitting electrons, apertured cathode and anode electrodes coupled to said electron emitting means for shaping the electron beam and a voltage source for impressing an accelerating voltage -between said cathode and anode electrodes, and wherein said beam deflection means is an electrostatic deflection device constituted of a pair of upper and lower deflection electrodes which are disposed in opposed relation with respect to the path of the undeflected electron -beam on either side thereof, said upper and lower deflection electrodes being connected to said cathode and anode electrodes respectively, so that the deflection of the electron beam is constantly maintained irrespective of variations in the accelerating voltage applied between the cathode and anode electrodes.

2. Apparatus as defined in claim 1 wherein said upper deflection electrode has a portion thereof extended along the emission line of the undeflected electron beam With an aperture therein, said aperture being positioned between said piece of the vaporable material and the substrate so that the vaporized particles of vaporable material can unobstructedly pass through the aperture.

3. Apparatus as defined in claim 2, which further comprises preventing means for preventing scattered electrons from reaching said substrate, said preventing means being composed of a magnetic field source mounted on the upper deflection electrode at the extended portion thereof to provide a parallel magnetic eld in a space between the extended portion of the upper deflection electrode and the substrate, the direction of the magnetic field being at a right angle to the emission path of the electron beam and being parallel to the plane of the upper deflection electrode.

4. Apparatus as defined in claim 1, wherein said upper deflection electrode has a portion extended upwards?` therefrom, and said apparatus further comprises a ver tically extended electrode which is provided at a laterally opposed position to said upwardly extended portion of the upper deflection electrode in a space between the piece of the material and the substrate, said vertically extended electrode Ibeing impressed with a voltage sub-Y stantially the same as that of the anode electrode, thereby producing in said space an electrostatic deflection field which prevents electrons scattered by the piece of the vaporable material from reaching the substrate.

5. Apparatus as defined in claim 1, wherein said cathode electrode is grounded and said piece of the vaporable material is impressed with a voltage substantially the same as that of the anode electrode.

6. Apparatus as defined in claim 1, wherein there are a plurality of electron beams sources and their associated beam deflection means arranged in circumferentially spaced relation to each other, the plurality of the electron beams of the respective electron beam sources being directed to the same piece of the vaporable material by the respective beam deflection means.

7o Apparatus as defined in claim 1, wherein there are a pair of electron beam sources and their associated beam deilection means aligned in line so `as to be symmetrically opposite to each other and to lead the respective electron beams to the same piece of the material.

8. Apparatus as defined in claim 1, wherein there are a multiplicity of electron beam sources and their associated beam deiiection means and wherein there are pieces of vaporable materials disposed closely adjacent to each other under the substrate, said -pieces of the vaporable materials being positioned in the paths of the respective deliected electron beams emitted from the respective electron beam sources.

9. Apparatus as dened in claim 8, wherein said vapor-1 able materials are different from each other.

10. Apparatus as defined in claim 1, wherein there are a plurality of electron beam sources and their associated beam deflection means, the electron beams emitted from the plurality of the electron beam sources being led to the same piece of the vaporable material by the respective beam deflection means.

11. Apparatus as defined in claim 1, wherein there are a multiplicity of electron beam sources and their associated beam deflection means, and there are pieces of vaporable materials which are positioned in the paths of the respective deflected electron beams emitted from the respective electron beam sources and which are disposed closely adjacent to eac-h other under the substratea 12. Apparatus for depositing vaporized particles of vaporable material on a substrate, which comprises:

(a) an evacuated envelope;

(b) at least one electron beam source for emitting an electron beam in a lateral direction in the envelope, which comprises means for emitting electrons, aper tured cathode and anode electrodes coupled to said electron emitting means for shaping said emitted electrons into said beam and a voltage source for impressing a variable accelerating voltage between said cathode and anode electrodes;

(c) at least one beam deection means for electrostatically defiecting said electron beam downwards, said deiiection means being constituted by a pair of upper and lower deflectionl electrodes disposed above and below the initial electron beam emission line and opposed to each other, said upper and lower deection electrodes being connected to said cathode and anode electrodes, respectively, so that the deflection of the electron beam is maintained constant irrespective of variations in the accelerating voltage applied between the cathode and anode electrodes;

(d) at least one piece of vaporable material to be deposited positioned in the path of the deflected electron beam so that the piece is struck by the electron beam to vaporize at the struck portion; and

(e) at least one substrate supported in the envelope :above the initial electron beam emission line in a manner to oppose said piece of vaporable material, whereby only vaporized particles of the vaporable material are permitted to reach the opposing surface of the substrate.

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